Comment 1 for bug 602945

I think this bug are also related to the following bugs:

https://bugs.launchpad.net/ubuntu/+source/apt/+bug/539219
https://bugs.launchpad.net/ubuntu/+source/software-properties/+bug/579110

I have read the source codes of APT, Synaptic, software-properties, software-properties-gtk and Python-apt and I think you have to mount the CD/DVD to /cdrom/ because of this line:

string CDROM = _config->FindDir("Acquire::cdrom::mount", "/cdrom/")

This code can be found in:

Synaptic package: rcdscanner.cc and apt package: apt-pkg/cdrom.cc

And the meaning of this line is: If the value of the key "Acquire::cdrom::mount" is empty, then "/cdrom/" will be used.

That's why sometimes you have to create the symbolic link for "/cdrom/".

Well, for a normal user, how to assign the mount point to the key "Acquire::cdrom::mount"?
Now, I have found two ways:

In the console, run:

1. sudo synaptic --add-cdrom {mount point}. For example, sudo synaptic --add-cdrom /media/APTonCD/

OR

2. sudo apt-cdrom add --auto-detect

At this moment, I don't know why the value of the key "Acquire::cdrom::mount" becomes empty.
Also, for me, I could not submit any patch because I am not familiar with Python language.

Therefore, I wish my report can help someone to solve this problem.